Field of the Invention
The present invention is in the field of self-feeding shredding devices especially intended for treatment of elongated scrap materials, such as copper wire, mold runners, etc. Such reclaimable materials, for further processing, typically must be severed into discrete lengths within a predetermined size range.
While shredder devices heretofore known are effective to comminute certain types of materials, the processing of elongate materials presents substantial problems. This is especially so where it is desired simultaneously to sever the materials into short lengths and feed the material.
It is well known, for instance, that elongate materials, especially ductile materials such as copper wire, cannot be fed in an auger type conveyor since they tend to become wrapped about the auger flutes.
Additionally, in the processing of scrap of the type described with extant shredder units, the tendency to stall or jam in the shredder has been great, requiring frequent down time to clear the resultant jams. Also, conventional shredders operate at efficiencies proportional to the sharpness of the knives, necessitating frequent sharpening to maintain satisfactory performance. As an alternate means of avoiding jams, resort has been made to extremely heavy duty, high powered devices having a capacity well in excess of the power necessary for ordinary processing but keyed instead to the occasionally arising jam condition.
A common defect in devices heretofore used lies in their cutting of the scrap by the exertion of shearing forces between closely spaced stationary and rotating knives. If scrap is caught in the nip between relatively moving parts disposed adjacent the rotating axis of the moving cutting member, the shearing apparatus will usually be effective to sever the scrap and avoid a jam. If, however, scrap elements are caught between the moving and stationary knives at a position remote from the shaft axis, far greater forces must be exerted to achieve shearing.